Video camera systems are widely used for capturing video images for surveillance purposes in offices, banks, in parking lots, on the streets, in homes etc. or for monitoring purposes in a production line or similar. However, recordings from such camera systems may include one single interesting event representing a few seconds among hours of video that is of no particular interest at all. Hence, there are a couple of problems with such systems. It is for instance very difficult to find a relatively short event of interest in a very long video recording. Moreover, the recording of all video requires a lot of storage space. Therefore, many monitoring and surveillance video cameras is arranged to detect events or be triggered by an external signal indicating an event. This extra information is in some implementations used to indicate where in the vast video recording the events of interest are positioned. In other implementations these events triggers the recording of the video of the event. For some events the video following after the event is of most interest, for other events the video preceding the event is of most interest, and for yet other events it is a combination of the above that are of most interest. Hence a relatively small sized file or stream of video is generated and is transmitted for remote storing in relation to each event detection.
Moreover, a video camera may be arranged to detect a plurality of different events resulting in an increased risk of events detected in a video camera occurring simultaneously and thereby resulting in two files or streams including at least some identical video image frames and thereby using up additional storage space or bandwidth.
In EP0898770, an event capturing method is described. The method discloses a video camera and a video card capturing video images. The video images are buffered by a processor, which makes files of a predetermined size of the buffered images and stores these files in a working storage. The files are stored in a circular fashion in the working storage (i.e., the newest file replaces the oldest) until an event is detected. Then the file including the event and later post-event files are stored sequentially in the working storage. Once the recording of a video image file containing the event is completed, the file containing the event is renamed to identify it as a file which contains an event (“e.g., 100400EV.EXT”). The event capturing system then continues recording video images until the total number of post-event files, as defined by the user during setup, have been recorded. Each of these event and post-event files may contain video from more than one event. Upon completion of the recording of all post-event files, the event files (i.e., the renamed files) are all tagged and identified for storage in permanent storage.